Pass dpi to GC for converting points to pixels

dmcdougall · dmcdougall · commit 51611c8028b4 · 2012-09-09T13:30:38.000+01:00
diff --git a/lib/matplotlib/backends/backend_macosx.py b/lib/matplotlib/backends/backend_macosx.py
@@ -42,6 +42,7 @@ def __init__(self, dpi, width, height):
         self.width = width
         self.height = height
         self.gc = GraphicsContextMac()
+        self.gc.set_dpi(self.dpi)
         self.mathtext_parser = MathTextParser('MacOSX')
 
     def set_width_height (self, width, height):
diff --git a/src/_macosx.m b/src/_macosx.m
@@ -425,6 +425,7 @@ - (int)index;
     NSSize size;
     int level;
     CGFloat color[4];
+    float dpi;
 } GraphicsContext;
 
 static CGMutablePathRef _create_path(void* iterator)
@@ -849,6 +850,15 @@ static int _get_snap(GraphicsContext* self, enum e_snap_mode* mode)
     return Py_None;
 }
 
+static PyObject*
+GraphicsContext_set_dpi (GraphicsContext* self, PyObject* args)
+{
+  if (!PyArg_ParseTuple(args, "f", &(self->dpi))) return NULL;
+
+  Py_INCREF(Py_None);
+  return Py_None;
+}
+
 static PyObject*
 GraphicsContext_set_linewidth (GraphicsContext* self, PyObject* args)
 {
@@ -862,6 +872,8 @@ static int _get_snap(GraphicsContext* self, enum e_snap_mode* mode)
         return NULL;
     }
 
+    // Convert points to pixels
+    width *= self->dpi / 72.0;
     CGContextSetLineWidth(cr, width);
 
     Py_INCREF(Py_None);
@@ -3202,6 +3214,11 @@ static void _data_provider_release(void* info, const void* data, size_t size)
      METH_VARARGS,
      "Sets the current stroke and fill color to a value in the DeviceGray color space."
     },
+    {"set_dpi",
+     (PyCFunction)GraphicsContext_set_dpi,
+     METH_VARARGS,
+     "Sets the dpi for a graphics context."
+    },
     {"set_linewidth",
      (PyCFunction)GraphicsContext_set_linewidth,
      METH_VARARGS,
